Device for storing gas under pressure

ABSTRACT

A device for storing gas includes at least one container ( 1 ) for gas, of the high pressure type, that has an outlet conduit with which is associated a branch ( 5 ) ensuring a closeable calibrated loss. The gas is in gaseous phase in this container over a range of pressures extending from about 40 to 250 bars and preferably from 50 to 200 bars and over a range of temperatures extending from about 15° K to 210° K and preferably from 20° K to 200° K. The device includes a thermally insulating envelope ( 2 ) in which the container ( 1 ) is disposed.

[0001] The invention relates to the storage and transportation of gasand more particularly to a device for the storage of gas under pressurepermitting the storage and transportation of gas in a form that does notpreliminarily require long and difficult treatment.

[0002] At present, gas is stored and transported in containers, in theliquid phase, or in the gaseous phase under pressure at ambienttemperature.

[0003] The liquefaction of the gases is financially and energeticallycostly; particularly, in the case of hydrogen, the temperature is verylow (20° K), the latent heat is high, and it is necessary to passthrough an ortho-para transformation phase.

[0004] The storage under pressure (so called HP storage), for exampleabout 200 bars, requires relatively heavy cylinders, for a relativelysmall quantity of gas. The increase in pressure (storage under very highpressure, or VHP) implies in the present state of the art, cylindersthat are wound with filament, but these cylinders are very costly, andthe compression means are not adapted for high flow rates; moreover, fora gas such as hydrogen, storage at 700 bars at 290° K represents only225 Nm³ of gas per cubic meter of volume of the container, which is tosay less than 60% of the volume in liquid phase at two atmospheres atabsolute pressure (750 Nm³ of gas per cubic meter of volume of thecontainer).

[0005] As a result, in such a case, the placing of gas under very highpressure is not of much interest.

[0006] The invention has for its object to overcome these drawbacks ofthe known devices, and more particularly to prevent storing,particularly for its transportation, the maximum of gas in the smallestvolume and weight possible, at least cost.

[0007] To this end, the invention relates to a device for the storage ofgas under pressure, characterized in that it comprises at least onecontainer for the gas of the high pressure type, comprising an outletconduit with which is associated a means ensuring a closeable calibratedloss, the gas being in the gaseous condition in this container over arange of pressures extending from about 40 to 250 bars and preferablyfrom 50 to 200 bars and over a range of temperatures extending fromabout 15° K to about 210° K, and preferably 20° K to 200° K, and athermal insulation envelope in which the container is disposed.

[0008] Thanks to these characteristics, for example for hydrogen, it ispossible to process large quantities of gas in a short time by means ofconventional compression installations of high flow rate, without theortho-para transformation which is highly consumptive of energy, and byusing cylinders of relatively low weight using materials conventionallyselected.

[0009] The invention can moreover have one or several of the followingcharacteristics:

[0010] the container comprises means for recovering cold from theexpansion of the gas;

[0011] the container is provided with means forming a heat exchangeradapted to be used before its filling with cold gas so as to cool itbefore its filling;

[0012] the container comprises an outlet conduit provided with an outletcontrol valve, and the means ensuring a closeable calibrated losscomprise a parallel branch on the valve;

[0013] the device comprises several containers within an envelope;

[0014] the device comprises at least one container within a Dewarcontainer, other than the container, of liquid nitrogen;

[0015] the container contains a gas at a pressure of the order of 200bars;

[0016] the container contains hydrogen in gaseous phase, and at atemperature comprised in a range extending from about 40° K to 120° K;

[0017] the container contains hydrogen in gaseous phase, and at atemperature of the order of 80° K, for example 77° K;

[0018] the container contains helium in gaseous phase, and at atemperature comprised within a range extending from about 20° K to 80°K;

[0019] the container contains neon in gaseous phase, and at atemperature comprised in a range extending from about 50° K to about 70°K;

[0020] the container contains carbon monoxide in gaseous phase, and at atemperature comprised in a range extending from about 140° K to 200° K;and

[0021] the container contains methane in gaseous phase, and at atemperature comprised within a range extending from about 145° K to 200°K.

[0022] Other characteristics and advantages of the invention will becomeapparent from the following description of embodiments of the inventiongiven by way of nonlimiting examples, illustrated by the accompanyingdrawings, in which;

[0023]FIG. 1 is a schematic longitudinal cross section of a deviceaccording to a first embodiment of the invention, which can particularlybe a device for storing hydrogen,

[0024]FIG. 2 is a schematic longitudinal cross sectional view of adevice according to a second embodiment of the invention,

[0025]FIG. 3 is a schematic transverse cross sectional view of a thirdembodiment of the invention,

[0026]FIG. 4 is a schematic transverse cross sectional view of a deviceaccording to a fourth embodiment of the invention, and

[0027]FIG. 5 is a schematic longitudinal cross sectional view of amodified container to be used with another embodiment of the deviceaccording to the invention.

[0028] The device according to the invention shown in FIG. 1 comprises acontainer for gas in gaseous phase, in the form of a cylinder 1,surrounded by a thermally insulating envelope 2 generally double walled.

[0029] The cylinder is a high pressure cylinder compromising an outletconduit provided with a swan's neck 3 at the end of which is disposed anoutlet control valve with which is associated in parallel a branch 5ensuring a closeable calibrated escape at the outlet of the conduit.

[0030] The gas contained in the cylinder is in this case hydrogencompressed to 200 bars in gaseous phase and at a temperature of theorder of 80° K, more precisely in this case 77° K, which avoids anyortho-para transformation, but in fact the range of possible pressuresfor hydrogen extends from about 50 to 250 bars and the range of thetemperatures from 40° K to 120° K. In the case of 80° K, 200 bars iswell adapted to constitute a supply capacity for a fuel cell for anelectric vehicle motor, and the escape necessary, in the absence ofcooling apparatus of the device, can well be used to maintain the cellas to temperature and/or to recharge the storage batteries.

[0031] The envelope 2 insulating the cylinder from the externalsurroundings is designed as a function of the admissible quantity ofloss, which is to say the quantity of loss possible to recharge thebatteries or to supply another device. There can for example be chosenan envelope 2 with high thermal insulation power of the so-called superinsulation type (that is, S.I. type) under vacuum so as to limit theconsumption of gas when the cell is not used; the “super insulation” canbe of the conventional type or with one or several internal shields 6connected as we will be seeing later, as needed. In the case of use foran electric motor vehicle with a fuel cell, the best solution consistsin using an envelope 2 of super insulation under vacuum with anarrangement of associated shields 6, with at least one end insulated bya foam material (FIG. 1). In this case, the loss necessary to maintainthe pressure below 200 bars permits generating electric power of about300 watts.

[0032] In the device shown in FIG. 1, the bottom of the cylinder isseparated from the bottom of the envelope by a centering partition 7constituted by a short column pierced with a longitudinal canal in theends of which are inserted projections respectively of the cylinder andof the envelope. The opposite end of the envelope has a neck whosediameter is slightly greater than the diameter of the cylinder so thatthe cylinder can be introduced into the envelope, and this neck, forexample of stainless steel, epoxy glass or Inconel (trademark), isprovided with a plug 8 of thermally insulating foamed material traversedby the outlet conduit of the cylinder.

[0033] The outlet conduit of the cylinder can be prolonged within thelatter by means 9 for recovering cold produced by the expansion of thegas, comprising an expansion valve 91 and a heat exchanger 92; it isthus to the cold source constituted by these means 9, for example theheat exchanger 92, that the shield or shields 6 of the envelope 2 areconnected.

[0034] It should be noted that the device according to the invention,for storage of gas in compressed gas phase, permits multiplying aboutthree times the transport capacity for hydrogen relative to knowndevices, and moreover it is possible to decrease particularly thepressure (to about 50 bars) while transporting however the same quantityof hydrogen as in the same volume pressurized at 200 bars at ambienttemperature, with a substantial gain as to the mass of the device.

[0035] As has been seen, as a modification, the envelope could containone or several shields (for example up to five shields) and a foammaterial on opposite sides of each shield.

[0036] The embodiment of FIG. 2, in which the elements corresponding tothose of FIG. 1 have the same reference numerals, comprises such anenvelope 2 with four shields connected to an internal source of cold andfive layers 10 of foam (or other thermal insulations); the cylinder 1 ofthis FIG. 2 is identical to that of FIG. 1, except that because of thedifference of internal structure of the envelope, it does not have acentering projection, and its outlet conduit is provided with a doubleswan's neck 3.

[0037] The envelope can also be independent of the high pressurecylinder; it could for example consist of a Dewar that is dry orrefrigerated with liquid nitrogen.

[0038]FIG. 3 shows an embodiment in which the envelope is a dry Dewarhaving a transverse cross section of rectangular shape and in whichthree cylinders 1 extend in parallel in a same plane and are juxtaposedside by side. FIG. 4 shows an embodiment in which the envelope 2 is aDewar having a transverse cross section of circular shape and in whichseven cylinders 1 extend in parallel and are disposed side by side; oneof the cylinders is disposed centrally with respect to the transversecross section of the envelope, and the six others are distributed aboutthe central cylinder; the space between the cylinders, and between thecylinders in the envelope, can be filled with liquid nitrogen 11; as amodification, the cylinders can be replaced by tubes connected “inseries” so as to constitute a serpentine, one of the two end tubes beingprovided with a conduit with a swan's neck with a valve and a branch(not shown), and if desired recovering means of the cold of expandingthe gas, like the cylinders of the embodiments of FIGS. 1 and 2. Thepresence of liquid nitrogen ensures substantially autonomy withoutdegassing, and in this case the escape can be stopped by closure of theoutlet conduit downstream of the valve 4.

[0039]FIG. 5 shows an embodiment in which the cylinder is associatedwith means forming an exchanger 12 permitting the preliminary cooling ofthe latter before its filling with cold gas when it is at ambienttemperature. These means forming exchanger 12 can be external to thecylinder, or internal as in FIG. 5, showing a high pressure cylinder 1traversed longitudinally by a conduit 121 through which can flow liquidnitrogen, this conduit carrying externally heat exchanged fins 122, theconduit 121 and the fins 122 constituting the means forming an exchanger12.

[0040] The invention can be applied to the storage, for eventualtransport, of gas other than hydrogen, in suitable ranges of temperatureand pressure.

[0041] For example, the devices according to the invention can be usedwith minimal modifications,

[0042] for helium between 20° K and 80° K, at about 200 bars, whichcorresponds to a density comprised between 1.5 and 0.7 times the densityof liquid helium at atmospheric pressure;

[0043] for neon between 50° K and 70° K, at about 200 bars, whichcorresponds to a density comprised between 0.9 and 0.5 times the densityof liquid neon at atmospheric pressure,

[0044] for carbon monoxide between 140° K and 200° K, at about 200 bars,which corresponds to a density comprised between 0.8 and 0.5 times thedensity of liquid carbon monoxide at atmospheric pressure,

[0045] for methane between 145° K and 200° K, at about 200 bars, whichcorresponds to a density comprised between 0.95 and 0.75 times thedensity of liquid methane at atmospheric pressure, or else 1.1 to 0.85times the density of the liquid methane at 7 atmospheres absolutepressure,

[0046] because of course the invention is not limited to the embodimentsdescribed above and illustrated, and others could be postulated withoutdeparting from its scope.

1. Device for storing gas under pressure, characterized in that it comprises at least one container (1) for the gas of the high pressure type comprising an outlet conduit with which is associated a means (5) ensuring a closeable calibrated loss, the gas being in gaseous phase in the container over a range of pressures extending from about 40 to 250 bars and preferably from 50 to 200 bars and over a range of temperatures extending from about 15° K to 210° K and preferably 20° K to 200° K, and a thermal insulation envelope (2) in which the container (1) is disposed.
 2. Device according to claim 1, characterized in that the container (1) comprises means (9) for recovering cold from the expansion of the gas.
 3. Device according to one of claims 1 and 2, characterized in that the container (1) is provided with means (12) forming a heat exchanger suitable to be used before its filling with cold gas so as to cool it before its filling.
 4. Device according to one of claims 1 to 3, characterized in that the container (1) comprises an outlet conduit provided with an outlet control valve (4), and the means ensuring a closeable calibrated loss comprises a branch (5) in parallel with the valve.
 5. Device according to one of claims 1 to 4, characterized in that the container (1) is a cylinder.
 6. Device according to one of claims 1 to 5, characterized in that it comprises several containers (1) within an envelope (2).
 7. Device according to one of the preceding claims, characterized in that it comprises at least one container (1) within a Dewar containing, in addition to the container, liquid nitrogen.
 8. Device according to one of the preceding claims, characterized in that the container (1) contains a gas at a pressure of the order of 200 bars.
 9. Device according to one of the preceding claims, characterized in that the container (1) contains hydrogen in gaseous phase, and at a temperature comprised within a range extending from about 40° K to 120° K.
 10. Device according to claim 9, characterized in that the container (1) contains hydrogen in gaseous phase, and at a temperature of about 80° K.
 11. Device according to one of claims 1 to 9, characterized in that the container (1) contains helium in gaseous phase, and at a temperature comprised within a range extending from about 20° K to 80° K.
 12. Device according to one of claims 1 to 9, characterized in that the container (1) contains neon in gaseous phase, and at a temperature comprised within a range extending from about 50° K to 70° K.
 13. Device according to one of claims 1 to 9, characterized in that the container (1) contains carbon monoxide in gaseous phase, and at a temperature comprised within a range extending from about 140° K to 200° K.
 14. Device according to any one of claims 1 to 9, characterized in that the container (1) contains methane in gaseous phase, and at a temperature comprised within the range extending from about 145° K to 200° K. 